Generally, golf balls are one of three types. A first type is a multi-piece wound ball wherein a vulcanized rubber thread is wound under tension around a solid or semi-solid core, and thereafter enclosed in a single or multi-layer covering of a tough, protective material. A second type of golf ball is a one-piece ball formed from a solid mass of a resilient material that has been cured to develop the necessary degree of hardness to provide utility. One-piece molded balls do not have a second enclosing cover. A third type of ball is a multi-piece non-wound ball that includes a liquid, gel or solid core of one or more layers and a cover having one or more layers formed over the core.
Attempts to improve and/or optimize performance characteristics in golf balls are typically directed toward achieving better feel when the ball is struck with a golf club, and also allowing for increased or optimum distance while at the same time adhering to the rules set forth by the United States Golf Association (U.S.G.A.) regarding the physical characteristics and performance properties of golf balls. These rules specify that the weight of a golf ball shall not be greater than 1.620 ounces, the diameter of the ball shall not be less than 1.680 inches and the velocity of the ball shall not be greater than 255 feet per second (250 feet per second with a 2% tolerance level). The U.S.G.A. rules also specify that the overall maximum distance a golf ball should travel (the “Overall Distance Standard” or “ODS”) shall not exceed an average distance (in carry and roll) greater then 280 yards, plus a 6% tolerance level (296.8 yards total). Recently, a new ODS was instituted by the USGA. This new ODS methodology utilizes an indoor test range (“ITR”) that consists of a ball launcher to launch the golf ball and a 70 foot tunnel into which the golf ball is launched. The tunnel consists of several stations of ballistic light screens. The ball launcher shoots the golf ball into the tunnel at specific, predetermined launch conditions (speed, spin rate and launch angle). The light screens are arranged such that the location of the golf ball may be determined on an X/Y/Z coordinate system. The new distance limit is 317 yards with a test tolerance of 3 yards, for a total of 320 yards maximum, when the golf ball is launched at 256 feet per second.
Over the years, attempts to improve characteristics such as feel and durability have centered on the materials used to form the various layers of a golf ball. Improvements in spin and distance characteristics are usually directed toward the actual construction and physical makeup of the golf ball. The use of one or more intermediate layers between a core and a cover layer to achieve such improvements is known in the art. The thickness and/or material hardness of each layer may also be varied in order to achieve a desired property.
In general, there is a natural transfer of energy that occurs within a golf ball when the ball is struck by a golf club. Energy is transferred from the club face to the golf ball cover, and then subsequently transferred through each layer beneath the cover. In solid non-wound golf balls employing spherical layers, energy transfer is generally a function of the thickness and material composition of a given layer. Therefore, varying either the thickness of a given layer and/or the material from which a layer is made affects the efficiency of energy transfer occurring within a golf ball and consequently affects the overall performance characteristics of that ball.
In wound, liquid or fluid core, and solid multi-layer golf balls, covers are placed around the preformed cores by techniques such as injection molding, compression molding, casting etc. When the cover is placed on the core, dimples are formed in the outer surface of the cover. This invention is concerned with the cover and/or coatings of a golf ball.
There exists a need for a golf ball design that assists a golfer in determining the approximate temperature of a golf ball and the ball's suitability for play in a given set of weather conditions. Knowing the ball temperature allows a golfer to determine when the ball is capable of delivering maximum performance characteristics, such as spin and overall distance. This is particularly true for golf balls having particular properties, such as a liquid or fluid-filled core. The fluid in the core will behave differently at different temperatures.
Golf balls having surfaces that incorporate dyes that change color due to an environmental change are known in the prior art. In this regard U.S. Pat. Nos. 5,938,544 and 5,823,891 to Winskowicz disclose golf balls which incorporate microencapsulated dyes in the surface thereof. These dyes change color upon prolonged exposure to water. The invention of these patents is useful for indicating when a golf ball becomes a “water ball” as a result of a prolonged immersion in water. The dyes in question change color upon immersion and remain colored; they do not revert back to their original color.
Thermochromic materials have been incorporated into the face of a golf club for purposes of indicating the point of impact between a golf ball and a golf club face. See, for example, U.S. Pat. No. 5,597,361 to Hope, and U.S. Pat. No. 5,805,245 to Davis, which discloses the use of thermochromic liquid crystals to indicate temperatures over different ranges. Similarly U.S. Pat. No. 5,394,824 to Johnson Jr. discloses the use of thermochromic dyes to indicate the point of impact of a tennis ball with a tennis court. Finally, the incorporation of thermochromic dyes into printing inks is disclosed in U.S. Pat. No. 4,717,710 to Shimizu et al.
None of the patents discussed above discloses the use of a layer of a thermochromic material on the surface of a golf ball for purposes of indicating the temperature of said golf ball, or the use of a material, such as a leuco dye, in a coating for purposes of indicating the temperature of said golf ball.